(a) Field of the Invention
The present invention relates to an encoding apparatus and an encoding method of a multiple input multiple output (MIMO) communication system. More particularly, the present invention relates to an encoding apparatus and an encoding method that may be applied to multiple input multiple output (MIMO) communication systems with different numbers of antennas.
(b) Description of the Related Art
In a multiple input multiple output (MIMO) technology, transmitting and receiving efficiency of data is improved by using multiple transmitting antennas and multiple receiving antennas.
The MIMO technology may be divided into a spatial multiplexing technique and a spatial diversity (SD) technique in accordance with a data transmission method. In the spatial multiplexing technique, different data items are simultaneously transmitted from a transmitter to a receiver using the multiple transmitting antennas so that data may be transmitted at a higher speed without increasing bandwidth of a system. On the other hand, in the SD technique, the same data is transmitted by the transmitter using the multiple transmitting antennas to obtain transmission diversity.
In addition, the MIMO technology may be divided into an open loop method and a closed loop method in accordance with whether channel information is fed back from the receiver to the transmitter or not. In the open loop method, data is transmitted by the transmitter without the channel information being fed back from the receiver. On the other hand, in the closed loop method, the data is transmitted by the transmitter with the channel information being fed back from the receiver. In the open loop method, amounts of calculations are smaller than those in the closed loop method, however a diversity gain, a data rate, and a decoding complexity are contrary to each other.
A MIMO communication system is applied to various long term evolution (LTE) and wireless local area network (WLAN) standards. In the MIMO communication system, an encoder of the transmitter selects an optimal precoding matrix using the channel information fed back from the receiver, and combines the precoding matrix with data items of respective layers in order to transmit the data items to the multiple transmitting antennas. When the number of channel environments and antennas varies, an encoder suitable for the number of channel environments and antennas is required. Therefore, in a state where the numbers of channel environments and antennas are different from each other in various standards, new encoders must be designed.